Pushable Cable

ABSTRACT

A cable assembly may be provided. The cable assembly may comprise a conductor core and a binding element. The binding elements may be configured helically around the conductor core. In addition, the binding element may be configured to, when the cable assembly is pushed through a conduit having at least one sweep, eliminate buckling of the cable assembly. Moreover, the binding element may be configured to cause a first pushing force on the cable assembly having a magnitude less than a second pushing force on the cable assembly corresponding to pushing the cable assembly through the conduit without the binding element on the conductor core.

RELATED APPLICATION

This application is a continuation-in-part (CIP) of U.S. applicationSer. No. 11/923,001, filed Oct. 24, 2007, which is incorporated hereinby reference. Furthermore, under provisions of 35 U.S.C. § 119(e),Applicants claim the benefit of U.S. Provisional Application No.60/939,153, filed May 21, 2007, which is incorporated herein byreference.

COPYRIGHTS

All rights, including copyrights, in the material included herein arevested in and the property of the Applicants. The Applicants retain andreserve all rights in the material included herein, and grant permissionto reproduce the material only in connection with reproduction of thegranted patent and for no other purpose.

BACKGROUND

Electrical cables may be used to transfer power from an electricaldistribution transformer. For example, 600V underground (UD) electricalcables are conventionally used to carry electrical power from thetransformer to a meter box (e.g. on a building) by direct burying the UDelectrical cables in the ground between the transformer to the meterbox. In conventional systems, however, the UD electrical cable issometimes pulled into a polyvinyl chloride (PVC) conduit or apolyethylene duct that is buried in the ground between the transformerand the meter box. Thus, the conventional strategy is to pullconventional UD electrical cables in a conduit that is buried in theground between the transformer and the meter box. This often causesproblems because the conventional strategy is time consuming because, inorder to pull the conventional UD electrical cable through a conduit, aline must be “blown” through the conduit from one end to another usingcompressed air. Then the line must be used to pull a “pull rope” backthrough the conduit. Next, a “Kellum Grip” must be attached between anend of the conventional UD electrical cable and an end of the pull rope.Then the pull rope is pulled back through the conduit thus pulling theconventional UD electrical cable through the conduit.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter. Nor is this Summaryintended to be used to limit the claimed subject matter's scope.

A cable assembly may be provided. The cable assembly may comprise aconductor core and a binding element. The binding element may beconfigured helically around the conductor core. In addition, the bindingelement may be configured to, when the cable assembly is pushed througha conduit having at least one sweep, eliminate buckling of the cableassembly. Moreover, the binding element may be configured to cause afirst pushing force on the cable assembly having a magnitude less than asecond pushing force on the cable assembly corresponding to pushing thecable assembly through the conduit without the binding element on theconductor core.

Both the foregoing general description and the following detaileddescription provide examples and are explanatory only. Accordingly, theforegoing general description and the following detailed descriptionshould not be considered to be restrictive. Further, features orvariations may be provided in addition to those set forth herein. Forexample, embodiments may be directed to various feature combinations andsub-combinations described in the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this disclosure, illustrate various embodiments of the presentinvention. In the drawings:

FIGS. 1A and 1B are diagrams of a pushable cable assembly;

FIG. 2 shows a graph illustrating pushing forces; and

FIG. 3 shows a binding element reel.

DETAILED DESCRIPTION

The following detailed description refers to the accompanying drawings.Wherever possible, the same reference numbers are used in the drawingsand the following description to refer to the same or similar elements.While embodiments of the invention may be described, modifications,adaptations, and other implementations are possible. For example,substitutions, additions, or modifications may be made to the elementsillustrated in the drawings, and the methods described herein may bemodified by substituting, reordering, or adding stages to the disclosedmethods. Accordingly, the following detailed description does not limitthe invention.

Consistent with embodiments of the invention, a cable assembly with abinding element (e.g. “skid wire” or “outer element”) may be provided.The binding element (e.g. helically applied) may be configured tooptimize pushing the cable assembly into a conduit or duct. Embodimentsof the invention may aid in pushing the cable assembly into the conduitor duct with minimum force. Accordingly, a person or a mechanicalcapstan may be able to create enough force to push the cable assemblyinto the conduit or duct without the cable assembly “bird caging,”buckling, or otherwise deforming. “Bird caging” may be characterized byconductors in a cable assembly fanning out due to a pushing (e.g.compressing) force being applied to the cable assembly to create a spacein the cable assembly between the cable assembly's conductors that takeson a bird cage's characteristics. To minimize the pushing force and tolimit the bird caging, buckling, or other deforming issues, a bindingelement (e.g. a helically applied outer wire) may be applied to thecable assembly's exterior.

Embodiments consistent with the invention may comprise a cable assembly.The cable assembly may comprise a conductor core comprising at least oneconductor. In addition, the cable assembly may comprise a bindingelement configured helically around the conductor core. The bindingelement may be configured to, when the cable assembly is pushed througha conduit having at least one sweep: i) eliminate buckling of the cableassembly; and ii) cause a first pushing force on the cable assembly tohave a magnitude less than a second pushing force on the cable assemblycorresponding to pushing the cable assembly through the conduit withoutthe binding element on the conductor core.

FIGS. 1A and 1B show a diagram of a pushable cable assembly 100. Asshown in FIGS. 1A and 1B, assembly 100 may include a conductor core 105and a binding element 110 (e.g. outer element.) Conductor core 105 maycomprise a plurality of conductors (e.g. a first conductor 115, a secondconductor 120, and a third conductor 125.) The plurality of conductorsin conductor core 105 may be twisted in a “right-hand” lay, a“left-hand” lay, or may be in parallel without being twisted. Moreover,the plurality of conductors in conductor core 105 may be twisted in analternating “right-hand” lay “left-hand” lay helix (or “S-Z” strand) to,for example, minimize stresses on conductor core 105.

The plurality of conductors may include any number of conductors (e.g.insulated or otherwise) and may include any number of ground wires ormay not include a ground wire. Any one or more of the conductors inconductor core 105 may be configured to be a neutral wire, or none ofthe conductors in conductor core 105 may be configured to be a neutralwire. Any one or more of the conductors in conductor core 105 may havean insulation color indicating those any one or more of the conductorsin conductor core 105 as a neutral(s). Furthermore the conductors inconductor core 105 may all be the same size or they may varyindividually or in any sub-combination by size. In addition, theconductors in conductor core 105 may all be made of the same material(e.g. copper, aluminum, etc.) or they may vary individually or in anysub-combination by material. Also, the conductors in conductor core 105may all be stranded or solid or they may vary individually or in anysub-combination by being stranded or solid.

Binding element 110 may be applied helically to the exterior ofconductor core 105. Binding element 110 may be, but is not limited to,metallic, non-metallic, electrically conductive, or non-conductivematerials. Binding element 110 may comprise, but is not limited to, awire 130 that may be coated with a coating material 135. Wire 130 maycomprise, but is not limited to, a metallic, non-metallic, electricallyconductive, or non-conductive material. Coating material 135 maycomprise, but is not limited to, polyethylene, polyvinyl chloride (PVC),or nylon. Binding element 110's cross-sectional shape may be, but is notlimited to, circular, oval, or any other shape. Moreover, bindingelement 110 may also be optimized to be of adequate hardness so that itminimizes deformation to binding element 110 and therefore minimizessurface contact between binding element 110 and a surface that bindingelement 110 slides across.

As stated above, binding element 110 may be electrically non-conductive.For example, users of cable assembly 100 may be concerned about whetherbinding element 110 needs to be grounded in an enclosure or transformerwhen a cable (such as cable assembly 100) is terminated in the enclosureor the transformer. If binding element 110 is electricallynon-conductive, the need for grounding binding element 110 may beeliminated.

Electrically non-conductive binding element 110 may be made, forexample, of a polymer material or a nylon material such as the materialused in conventional lawn trimmers or monofilament fishing lines.Electrically non-conductive binding element 110, for example, may belarge enough to keep first conductor 115, second conductor 120, andthird conductor 125 off an interior of a conduit even going throughbends in the conduit when cable assembly 100 is installed in theconduit. Though not so limited, binding element 110 having a diameter ofat least 0.125″ may provide this feature.

Binding element 110 may be made of a material configured to be stretchedto a predetermined percentage of a length of the material withoutbreaking. For example, the material may elongate, for example, more than50% (e.g. several hundred percent) before binding element 110 breaks. Inother words, a length of the material two feet long may be stretched tothree feet, four feet, or even six feet without the material breaking.

This stretching feature may be an advantage if binding element 110 hangson an interior of a conduit while cable assembly 100 is being installedin the conduit (e.g. pushed through the conduit.) In other words, thistype of stretchable binding element 110 may allow binding element 110 tostretch, but minimizes breakage of binding element 110 duringinstallation. If binding element 110 does not include this stretchingfeature (e.g. if it were made of aluminum that may only stretch lessthan 5% before breakage,) breakage of binding element 110 may present aproblem during cable assembly 100's installation.

Moreover, non-conductive binding element 110 made of, for example, apolymer or a nylon material may have a low coefficient of friction. Thismay be achieved by having the right combination of hardness (ordurometer) and surface finish on binding element 110. With smallersurface imperfections (e.g. better surface finish), the lower thefriction in sliding. Furthermore, it may be advantageous to not have thematerial from which binding element 110 is made to be too hard in orderto minimize potential indentation into a conductors in an assembly (e.g.first conductor 115, second conductor 120, and third conductor 125.) Inaddition, non-conductive binding element 110 made of, for example, apolymer or a nylon material, may have good toughness and can take a lotof abrasion without damage. For example, non-conductive binding element110 may further protect the conductors in the assembly by taking most ofthe abrasion during installation instead of the insulation of theassembly's conductors being damaged.

Coating material 135 may comprise a sheath material introduced in pelletform to an extruder that heats and directs the sheath material onto wire130. Consistent with embodiments of the invention, the sheath materialmay comprise a material (e.g. sheath pellets) having a lubricatingmaterial included in the sheath material. In other words, the sheathpellets may have the lubricating material formed directly in the sheathpellets. Or, when the sheath pellets do not have the lubricatingmaterial formed in the sheath pellets (i.e. lubricating-material-freesheath pellets), the lubricating material may be introduced into theextrusion process separately, for example, as separate lubricatingmaterial pellets. Consequently, the lubricating material pellets and thelubricating-material-free sheath pellets may be introduced into anextruder that heats, mixes, and directs the mixed material onto wire 130to form coating material 135.

The lubricant material may comprise fatty amides, hydrocarbon oils,fluorinated organic resins, and mixtures thereof. Fatty amides andmetallic fatty acids may include, but are not limited to, erucamide,oleamide, oleyl palmitamide, stearyl stearamide, stearamide, behenamide,ethylene bisstearamide, ethylene bisoleamide, stearyl erucamide, erucylstearamide, and the like. Hydrocarbon oils may include, but are notlimited to, mineral oil, silicone oil, and the like. Lubricatingmaterials consistent with embodiments of the invention may includeplasticizers, dibasic esters, silicones, anti-static amines, organicamines, ethanolamides, mono- and di-glyceride fatty amines, ethoxylatedfatty amines, fatty acids, zinc stearate, stearic acids, palmitic acids,calcium stearate, lead stearate, sulfates such as zinc sulfate, etc.,and the like. The above lubricating materials may be used individuallyor in combination. Furthermore, lubricating materials may includefluorinated organic resins, such as a polymer of one or more fluorinatedmonomers selected from tetrafluoroethylene, vinylidene fluoride,chlorotrifluoroethylene, and the like. The fluorinated resin may be usedin a powder, emulsion, or aqueous dispersion.

Binding element 110 may be made of two pieces (e.g. wire 130 and coatingmaterial 135), may be one piece, or in any other construction.Consistent with embodiments of the invention, once pushable cableassembly 100 is constructed, the lubricating material may bloom, migratetoward binding element 110's exterior, and permeate binding element 110.Binding element 110 may be porous, thus enabling the lubricatingmaterial to migrate toward binding element 110's exterior surface.Binding element 110's exterior may contain sufficient lubricatingmaterial to provide an exterior surface with a reduced coefficient offriction. In other words, binding element 110 may comprise or otherwiseinclude any material that may be configured to cause a low or lessenedcoefficient of friction between cable assembly 100 and a conduit orduct. For example, the coating material may excrete or leach alubricant.

To limit the bird caging, buckling, or other deforming issues, bindingelement 110 may be configured to hold or otherwise bind cable assembly100's conductor core 105 together. For example, binding element 110 maybe sufficient to hold conductor core 105's plurality of conductorstogether at least in the presence of a force sufficient to push cableassembly 100 through a conduit or duct. For example, the aforementionedforce may comprise a force applied by a person continuously pushingseveral hundred feet of cable assembly 100 through a conduit or ductbetween an electrical transformer and a meter box mounted to a building.The conduit or duct may have a sweep (e.g. a sweeping bend in theconduit or duct of approximately ninety-degrees or otherwise.)Accordingly, binding element 110 may be configured to hold or otherwisebind conductor core 105's conductors together in the presence of atleast this type of force, for example.

Furthermore, binding element 110 may be applied to conductor core 105'sexterior in order to minimize the aforementioned pushing force. Bindingelement 110 may be configured to contact the conduit or duct during apushing installation process. Consequently, binding element 110 mayminimize the pushing force by lessening the friction between assembly100 and the conduit or duct. In other words, binding element 110 maycause less friction between cable assembly 100's exterior and theconduit or duct than would be present if cable assembly 100 was pushedthrough the conduit or duct without binding element 110. For example,binding element 110 may reduce this frictional force between cableassembly 100's exterior and the conduit or duct down to a level that aperson could continuously push several hundred feet of cable assembly100 through the conduit or duct between an electrical transformer and ameter base.

Moreover, binding element 110 may enable this low frictional force evenwhen at least one sweep is present in the conduit or duct between theelectrical transformer and the meter box. For example, binding element110 may provide a plurality (e.g. three or more) of contact points that,in most cases, may prevent conductor core 105's conductors fromcontacting any portion of the conduit or duct during entrance and exitof a sweep during the aforementioned pushing process. As stated above,to minimize the pushing force and to limit bird caging, buckling, orother deformation issues, binding element 110 may be applied toconductor core 105's exterior. Binding element 110 may be helicallyapplied to conductor core 105's exterior. Moreover, binding element110's helical lay length may be optimized (or fall within an optimalrange) for best results in minimizing the pushing force and to limitingthe bird caging, buckling, or other deforming issues. For example,binding element 110's helical lay length may fall within an optimalrange to provide, for example, three or more points of contact that mayprevent conductor core 105's conductors from contacting any portion ofthe conduit or duct during entrance and exit of a sweep (e.g. sweepingninety-degree bend) during the aforementioned pushing process. A bendingradius of the sweep, the conduits or duct's diameter, and othergeometric constraints may be considered when optimizing the lay length.For example, the lay length may fall between approximately three totwelve inches and may be 6.5 inches. Moreover, binding element 110'shelical lay length may fall within an optimal range in order to keep theconductors from bird caging, buckling, or having other deforming issueswhen a compressive force is applied to cable assembly 100 during theaforementioned pushing installation process.

FIG. 2 shows a graph 205 illustrating pushing forces. For example, graph205 illustrates an operational example of forces that may be required topush cables through a two inch diameter PVC conduit system over thelength of the conduit system with conventional cables. Vertical blackbars 210 correspond to approximately ninety-degree sweeps. Element 215(the “HD HiScore, RTS w AL/HD skid wire, Standard H26” that is thebottom line in the legend designates the cable assembly with the helicalapplied outer wire) in graph 205 may correspond to embodiments of thepresent invention using binding element 110 (i.e. skid wire.) As shownin graph 205, the force to push through all four of the ninety-degreesweeps (shown as vertical black bars 210) at the end of the run is muchless for element 215 than any of the other conventional sample cablescompared. As shown in the FIG. 2 example, no more than 243 lbs. of forcewas needed to push 367 feet of cable through a conduit including twoninety-degree sweeps. In addition, FIG. 2 example shows no more than 362lbs. of force was needed to push 379 feet of cable through a conduitincluding three ninety-degree sweeps. In this operational example, allof the other conventional sample cables “stalled out” a mechanicalpushing device, which explains the abrupt end of data on the graph linescorresponding to the conventional sample cables.

FIG. 3 shows a binding element reel 305. As shown in FIG. 3, bindingelement 110 may be placed on binding element reel 305 prior to bindingelement 110 being applied to conductor core 105. Consistent withembodiments of the invention, binding element 110 may have an elastic orresilient memory. For example, while on binding element reel 305,binding element 110 may be helical with a first radius. However, whenbinding element 110 is removed from (or paid off) binding element reel305, binding element 110 may remain helical, but may return to a secondradius. The second radius may be smaller than the first radius. In otherwords, when removed from binding element reel 305, binding element 110may change from a helix with a larger radius to a helix with a smallerradius due to having an elastic or resilient memory.

When constructing cable assembly 100, binding element 110 may be paidoff binding element reel 305 and applied to a length of conductor core105. When a sufficient amount of binding element 110 is paid off bindingelement reel 305, binding element 110 may be cut with a first portion ofbinding element 110 having been place on conductor core 105 and a secondportion of binding element 110 remaining on binding element reel 305. Inthis way, binding element 110 may be applied to conductor core 105. Dueto binding element 110's aforementioned elastic or resilient memorycharacteristic, when binding element 110 is cut during theaforementioned application process, binding element 110 may tend to drawtightly to conductor core 105 rather than fanning out or “bird caging.”In other words, due to binding element 110 having the aforementionedresilient memory characteristic, binding element 110 may fit snugglyaround conductor core 105 once binding element 110 is paid off bindingelement reel 305, applied to conductor core 105, and cut.

While certain embodiments of the invention have been described, otherembodiments may exist. Further, any disclosed methods' stages may bemodified in any manner, including by reordering stages and/or insertingor deleting stages, without departing from the invention. While thespecification includes examples, the invention's scope is indicated bythe following claims. Furthermore, while the specification has beendescribed in language specific to structural features and/ormethodological acts, the claims are not limited to the features or actsdescribed above. Rather, the specific features and acts described aboveare disclosed as example for embodiments of the invention.

1. A cable assembly comprising: a conductor core; and a binding elementconfigured helically around the conductor core, the binding elementconfigured to, when the cable assembly is pushed through a conduithaving at least one sweep, eliminate buckling of the cable assembly andcause a first pushing force on the cable assembly having a magnitudeless than a second pushing force on the cable assembly corresponding topushing the cable assembly through the conduit without the bindingelement on the conductor core, the binding element being made of amaterial configured to be stretched to a predetermined percentage of alength of the material without breaking.
 2. The cable assembly of claim1, wherein the material is electrically non-conductive.
 3. The cableassembly of claim 1, wherein the binding element has a diameter of atleast 0.125 inches.
 4. The cable assembly of claim 1, wherein thepredetermined percentage is one of the following: 50% and greater than50%.
 5. The cable assembly of claim 1, wherein the predeterminedpercentage is between 50% and 100%.
 6. The cable assembly of claim 1,wherein the predetermined percentage is between 50% and 200%.
 7. Thecable assembly of claim 1, wherein the binding element has a resilientmemory characteristic configured to cause the binding element to fitsnuggly around the conductor core.
 8. The cable assembly of claim 1,wherein the binding element is configured to leach a lubricant.
 9. Thecable assembly of claim 1, wherein the least one sweep is substantiallyninety degrees.
 10. The cable assembly of claim 1, wherein the firstpushing force is between 5 pounds and 200 pounds and pushes the cableassembly through at least 340 feet of the conduit containing at leasttwo sweeps.
 11. The cable assembly of claim 1, wherein the first pushingforce is between 5 pounds and 200 pounds and pushes the cable assemblythrough at least 340 feet of the conduit containing at least threesweeps.
 12. A cable assembly comprising: a conductor core; and an outerelement placed around the conductor core, the outer element configuredto provide a plurality of contact points between the outer element and aconduit when the cable assembly is pushed through the conduit having atleast one sweep, the outer element being configured to prevent contactbetween the conductor core and the conduit, wherein the outer element ismade of a material that is electrically non-conductive.
 13. The cableassembly of claim 12, wherein the material comprising one of thefollowing: a polymer material and a nylon material.
 14. The cableassembly of claim 12, wherein the material is configured to be stretchedto a predetermined percentage of a length of the material withoutbreaking.
 15. The cable assembly of claim 14, wherein the predeterminedpercentage is one of the following: 50% and greater than 50%.
 16. Thecable assembly of claim 14, wherein the predetermined percentage isbetween 50% and 200%.
 17. The cable assembly of claim 12, wherein thematerial is soft enough to keep the outer element from indenting theconductor core.
 18. The cable assembly of claim 12, wherein a lay lengthof the outer element is between three and twelve inches.
 19. The cableassembly of claim 12, wherein the outer element is of sufficienthardness so that the outer element is substantially un-deformation whenthe cable assembly is pushed through the conduit.
 20. A cable assemblycomprising: a conductor core; and a binding element configured helicallyaround the conductor core, the binding element configured to allow aforce of between 5 pounds and 200 pounds push the cable assembly throughat least 340 feet of conduit containing at least two sweeps, wherein thebinding element is made of a material that is electricallynon-conductive and wherein the material is configured to be stretched toa predetermined percentage of a length of the material without breaking,the predetermined percentage being one of the following: 50% and greaterthan 50%.